class Solution {
    public int search(int[] nums, int target) {
        int left =0,right = nums.length-1;
        while(left<=right) {
            int mid = left +(right-left)/2;//防止溢出
            if(nums[mid]<target) left = mid+1;
            else if(nums[mid]>target) right = mid-1;
            else return mid;
        }
        return -1;
    }
}